On my laptop running Windows Server 2008, I found I was unable to receive an IP address on some wireless networks. After a bit of research, I found this Microsoft KB article detailing an issue with DHCP discovery. For conciseness, a short summary:
Under the following registry location, find the name of the affected network card (under <some number>\Description).

and locate the GUID you recorded in the last step. Under that service, create a new DWORD value named DhcpConnEnableBcastFlagToggle, and set its value to 1. Disable and re-enable the network interface, or renew your IP address, and it should get an IP address.